Patent GB-190401388-A (GB)
Title: Improvements in Fluid Pressure Brake Apparatus for Railway and like Vehicles.
Filed: 1904-01-19
Granted: 1904-12-15
Abstract: 1388. Westinghouse Brake Co. Jan. 19. Brakes.-Relates to means for maintaining the trainpipe pressure in case of leakage, in fluid-pressure brake systems, and also for restoring brake-cylinder pressure, during application of the brakes, by supply from the train pipe. The train-pipe pressure is maintained by the action of a regulating-device in which a diaphragm 24, Fig. 2, is subjected to trainpipe pressure through a pipe 13 and to a constant pressure in a chamber 22 and its enlargement 18, Fig. 1, which pressure is controlled by an equalizing-valve 15, shown as a separate valve in Fig. 1, but forming part of the driver's valve in the modifications shown in Figs. 6 and 10. The chamber 23, Fig. 2, of the regulating-valve is con - nected to the main-reservoir pipe 2, Fig. 1, by a pipe 12 and with the train pipe 3 by the pipe 13. The regulating-chamber 22 is connected by a pipe 14 to the equalizing-valve 15, and by a pipe 17 to the passage 26, Fig. 4, and port 28 in the feed valve attached to the driver's valve. The port 26 and train-pipe port 32 are simultaneously opened and closed to the valve-chamber by the slide valve 29, which has an additional port 27 to register with port 28 and is actuated by a piston 34 set to close the ports at normal train-pipe pressure. When charging, with the driver's valve in running position the train pipe and the regulating-chamber 22 are filled simultaneously, but the pressure in the latter rising more quickly, raises the diaphragm 36, Fig. 3, of the equalizing-valve against the train-pipe pressure always existing in the equalizing-reservoir 5, and vents into the train pipe through the valve 37 until the pressures on the diaphragms 24, 36 are all equal. If now the train pipe leaks, the pressure falls in chamber 23 and the valves 25 are opened to admit main reservoir air till the pressure again equals that in the chamber 22. On lowering the pressure in the equalizing-reservoir 5 to apply the brakes, the diaphragm 36 rises to vent the chamber 22 through the valve 37, while the train-pipe discharge port of the driver's valve is open, so that in the lap position again, with the passage to the feed valve closed, the pressures in the train pipe and the regulating-chamber are equal at the desired reduction, and leakage is compensated as before. For emergency application the reservoir 5 is vented to the atmosphere and therefore also the regulating-chamber 22 through the valve 37 and the train pipe. In the modification shown in Fig. 6, the regulating-chamber 22 is connected to a port 71 in the driver's valve casing leading to the equalizing-chamber 65 and having a port 70 in the seat of the driver's valve. The port 71 is normally closed by a valve 73 actuated by the equalizing- piston 66 so as to open simultaneously with the discharge valve 74 of the train pipe 3. The rotary valve, in addition to the ordinary ports, has a cavity 81, Fig. 8, which in running position connects the port 70, Fig. 7, with the preliminary discharge port 64 leading to chamber 65. Thus the train-pipe pressure is established in the regulating-chamber 22, port 70, cavity 81, chamber 65 and, through the open connection 75, in the equalizing-chamber 5. To apply the brakes, another cavity of the rotary valve is set to connect the port 64 but not port 70 with the exhaust 63, thus reducing the pressure in the chamber 65 and opening the port 71 and valve 74 till the required reduction is reached, whereupon the valve 73 returns to seal up the pressure in the pipe 17 and chamber 22 which acts to maintain the train-pipe pressure as before, the rotary valve being brought to the lap position. For an emergency application, the cavity in the valve connects both ports 64, 70 to the exhaust 63, the train pipe venting through the port 62, cavity 79, and port 63. In case of a hose bursting or parting, the pipe 12, Fig. 1, is closed by a cock to prevent the main reservoir from exhausting. In the modifications shown in Figs. 10 and 11 the regulating-chamber is connected to a port 71 in the train-pipe chamber of the equalizing-valve, opened as before simultaneously with the discharge valve 74 ; or they may both be controlled by one valve 73 as shown in Fig. 11. A chamber 85,86, Fig. 10, in the regulating-valve casing contains a loosely-fitting spring- governed piston 87 which operates a slide valve 25 to admit main-reservoir air from a pipe 12 to the train-pipe chamber 23 of the valve through the pipe 89 which may deliver to the train pipe near its junction with the pipe 13. The stem of the diaphragm 24 engages the spindle of a small spring-closed valve 90 to establish communication between the train-pipe chamber 23 and the chamber 85 in which main-reservoir pressure is set up round the piston 87. While charging, the small valve 90 being closed, the valve 25 is held closed by the spring 91 while the pressures equalize on both sides of piston 87. On applying the brakes, the regulating-chamber 22 is vented through the port 71 till the valve 73 is closed. Any leakage from the train pipe causes the diaphragm 24 to open the valve 90, and vent the main - reservoir pressure in the chamber 85, so that the piston 87 opens the port 92 to supply air to the train pipe. The valve 19, Figs. 1 and 12, for maintaining brake-cylinder pressure by supply from the train pipe, has two chambers separated by two opposite valves 42, 43 operated by a controlling-diaphragm, the pressure of which is adjusted by a spring 41. The wings of the valves abut and are of such a length that, when the diaphragm is in mid position, they are both off their seats. The valves are preferably loosely mounted so as to fit closely on their seats, and a light spring 44 may be employed to close the trainpipe valve 42. The spring 41 is adjusted to hold a safe brake-cylinder pressure sufficient to control the train so that on leaking down to such pressure the valves are both opened and pressure restored from the train pipe. In a modification shown in Fig. 13, a controlling-chamber 95 is connected to the triple valve and is adapted to exhaust to the atmosphere when the triple valve is at release position. A diaphragm 97 separates this chamber from a chamber 96 open to brake-cylinder pressure, and operates a valve 99 for equalizing the pressures on both sides of the diaphragm. The spindle 98 also engages the stem of a valve 102 to admit trainpipe air through the check valve 104. On applying the brakes, the triple valve seals up the chamber 95, and the brake-cylinder air raises the diaphragm, thus opening the valve 99 and filling the chamber 95 until the light spring 109 returns the diaphragm to its normal position. The spring 109 bears on a washer 110 which normally rests on a shoulder in the casing so as not to affect the valve 102. If now leakage occurs in the brake cylinder, the valve 102 is opened to restore pressure from the train pipe. On releasing the brakes, the chamber 95 is vented through the triple valve. Instead of venting through the triple valve, a valve 115, Fig. 16, may be provided and be actuated by a diaphragm 112 subjected to auxiliary-reservoir pressure through the pipe 111 and to train-pipe pressure through the pipe 113. The port 118 is normally held closed by the spring 120, but, on releasing the brakes, the increased train-pipe pressure moves the valve to exhaust the chamber 95. The casing forms a stop to the left of the spindle of the diaphragm as shown, so that a fall in train-pipe pressure does not affect the valve 115. In case of the triple valve sticking, the chamber 95 being exhausted uncovers the port 100 and allows the brake cylinder to exhaust through the valve 115.